Engine-driven, electrical generators are used in a wide variety of applications. Typically, an electrical generator utilizes a single driving engine directly coupled to a generator or alternator through a common shaft. The engine is also directly connected to a pressurized fuel source, such as diesel and/or natural gas, in order that the generator may be automatically activated in the event of a power outage. Upon activation of the generator, a fuel and air mixture is provided to the combustion chambers of corresponding cylinders of the engine. The fuel mixture in each combustion chamber is ignited causing an explosion within the cylinders. The explosive forces within the combustion chambers in the cylinders cause linear motion of the pistons within their corresponding cylinders. The linear motion of the pistons is converted into rotational motion by a crankshaft that, in turn, drives the alternator. As is conventional, the driven alternator generates electrical power.
In order to increase the operating efficiency of the generator, it is contemplated to utilize a diesel engine to drive the alternator. As is known, diesel engines may be operated utilizing both diesel fuel and natural gas as the fuel sources. These “bi-fuel” engines operate on diesel fuel for a first predetermined portion of the operating range of the engine and on a mixture of diesel and gaseous fuels for the remaining portion of the operating range. In order to insure proper operation of the engine, it is necessary to continually monitor the volume of gaseous fuel supplied to the engine. If too much gaseous fuel is provided, the engine may lose power or be damaged. On the other hand, if too little gaseous fuel is provided, the engine will operate at a less than optimum efficiency or emissions performance.
In order to regulate the flow of fuels to the engine, control systems of different types have been developed. By way of example, Rieck, U.S. Pat. No. 6,178,927 discloses a gas engine having a control system with a pilot control device for adjusting the operating state of the engine in response to changes in various monitored limiting conditions. A plurality of predetermined limiting conditions are defined such that the control system stops the engine if the operating point of the engine reaches any of the plurality of limiting conditions. In certain applications wherein the load conditions on a generator varies greatly, the operating point of the engine may approach the limiting conditions thereby resulting in the control system stopping the engine. As such, it is highly desirable to provide a more adaptable control system for the generator that adjusts to continually varying load conditions.
Therefore, it is a primary object and feature of the present invention to provide a method of controlling and regulating operation of a bi-fuel, engine-driven electrical generator set that maintains the engine within desired operating conditions.
It is a further object and feature of the present invention to provide a method of controlling and regulating operation of a bi-fuel, engine-driven electrical generator set that minimizes the emissions produced during operation of the engine.
It is a still further object and feature of the present invention to provide a method of controlling and regulating operation of a bi-fuel, engine-driven electrical generator set that is simple and inexpensive to implement.
In accordance with the present invention, a method is provided for controlling a bi-fuel generator set. The bi-fuel generator set includes a controller, a generator for generating logical power, and an engine for driving the generator. The method includes the steps of providing a flow of gaseous fuel to the engine and monitoring vibration of the engine during operation. A vibration signal is provided to the controller in response to vibration of the engine during operation. The vibration signal is compared to the first threshold such that if the vibration signal exceeds the first threshold, the controller reduces the flow of gaseous fuel provided to the engine.
The air temperature at the air intake of the engine is monitored and compared to a threshold. If the air temperature at the air intake of the engine exceeds the threshold, the controller reduces the flow of gaseous fuel provided to the engine. In addition, the electrical power produced by the generator is monitored. If the electrical power exceeds a threshold, the flow of gaseous fuel provided to the engine is cooled.
The method also includes providing coolant for cooling the engine. The temperature of the coolant is monitored such that if the temperature of the coolant exceeds the threshold, the flow of gaseous fuel provided to the engine is cooled. Diesel fuel is also provided to the engine. The volume of the diesel fuel provided to the engine is adjusted in response to the flow of gaseous fuel provided.
It is contemplated to compare the vibration signal to a second threshold such that if the vibration signal exceeds the second threshold, the controller terminates the flow of gaseous fuel to the engine. In addition, it is contemplated to determine maximum flow of gaseous fuel to the engine in response to a load on the engine and the air temperature of the air intake of the engine. The flow of gaseous fuel provided to the engine is then compared with the maximum flow of gaseous fuel. The flow of gaseous fuel provided to the engine is increased if the flow of gaseous fuel provided to the engine is less than the maximum flow of gaseous fuel. Further, if the vibration signal is less than the first threshold, the flow of gaseous fuel to the engine is also increased.
If the temperature of the coolant exceeds a first threshold, the flow of gaseous fuel to the engine is stopped. If the temperature of the coolant exceeds a second threshold, the engine is stopped.
In accordance with a further aspect of the present invention, a method is provided for controlling a bi-fuel generator set having a control, a generator for generating electrical power, and an engine for driving the generator. The method includes the steps of providing a flow of gaseous fuel to the engine and cooling the flow of gaseous fuel. The flow of gaseous fuel provided to the engine may be cooled if the electrical power exceeds a threshold and/or the temperature of the coolant of the engine exceeds a threshold.
The vibration of the engine during operation is monitored and a vibration signal is provided to the controller in response thereto. The vibration signal is compared to a threshold such that if the vibration signal exceeds the threshold, the controller reduces the flow of gaseous fuel provided to the engine. If the vibration signal is less than the threshold, the flow of gaseous fuel provided to the engine is increased. In addition, the vibration signal may be compared to a second threshold such that if the vibration signal exceeds the second threshold, the controller terminates the flow of gaseous fuel to the engine.
The method includes the steps of monitoring the air temperature at the air intake of the engine and adjusting the flow of gaseous fuel provided to the engine in response to the air temperature at the air intake. The temperature of the coolant for the engine is also monitored. If the temperature of the coolant exceeds a first threshold, the flow of gaseous fuel provided to the engine stops. If the temperature of the coolant exceeds a second threshold, the engine is stopped. The speed of the engine may also be monitored such that if oscillations in the speed of the engine are detected, the flow of gas provided to the engine may be reduced.
In accordance with a still further aspect of the present invention, a method of controlling a bi-fuel generator set is provided. The generator set includes a controller, a generator for generating electrical power, and an engine for driving the generator. The method includes the steps of providing diesel fuel to the cylinders of the engine for ignition and providing a flow of gaseous fuel to the engine. The operating conditions of the engine and the generator are monitored and the flow of gaseous fuel to the engine is adjusted in response to predetermined operating conditions on the engine.
It is contemplated to cool the flow of gaseous fuel provided to the engine under certain conditions. For example, the gaseous fuel provided to the engine may be cooled if the temperature of the coolant of the engine exceeds a threshold. Alternatively, the gaseous fuel provided to the engine may be cooled if the electrical power generated by the generator exceeds a threshold.
The step of monitoring the operating conditions of the engine may include the step of monitoring vibration of the engine during operation. Thereafter, a vibration signal may be provided to the controller in response to vibrations. The vibration signal is compared to a first threshold such that if the vibration signal exceeds the first threshold, the flow of gaseous fuel provided to the engine is reduced. If the vibration signal is less than the first threshold, the flow of gaseous fuel to the engine is increased. If the vibration signal is greater than a second threshold, the flow of gaseous fuel provided to the engine is terminated.
The air temperature at the air intake of the engine, the temperature of the coolant for the engine, and the speed of the engine may also be monitored. If the temperature of the coolant exceeds a first threshold, the flow of gaseous fuel to the engine is stopped. If the temperature of the coolant exceeds a second threshold, the engine is stopped. If oscillations are detected in the speed of the engine, the flow of gaseous fuel provided to the engine is reduced.